1. Field of the Invention
The present invention relates to an amino acid-enriched feed, industrially produced mixed feed or premix thereof which comprises using an amino acid fermentation broth or its treated solution (amino acid containing solution or suspension originating in an amino acid fermentation broth).
2. Description of the Background
Industrially produced mixed feed for various agriculturally useful animals or livestock (such as pig and poultry) is composed of various individual feeding materials (e.g. cereals, brans, vegetable oil meals, animal feeds, corn gluten meal (hereinafter, referred to as "CGM"), corn gluten feed (hereinafter, referred to as "CGF"), cane sugar molasses, starch cake, feed additives and the like). The composition of amino acids present in the feed causes great influence on the growth of animals. Usually L-lysine, L-threonine and L-tryptophane become limiting amino acids although they are dependent on the compounding ratio of individual components in the mixed feed. So industrially produced crystalline amino acids have been used as additives to the feed.
Amino acids such as L-lysine hydrochloride, L-threonine, L-tryptophane, etc. which are currently used as feed additive are prepared by fermentation thereby crude broth containing amino acid, inorganic salts, microorganism, saccharides, etc. is obtained, and the desired amino acid is separated from the broth, for example, by an ion-exchange resin treatment and crystallization processes. According to such processes the desired amino acid may be obtained in high purity. However, the processes have the disadvantage that installation investment is big and expensive sub-raw materials need to be used.
Amino acids for use as feed additive are not always required to have high purity as stated above. So, many attempts have also been made to utilize as feed additive a granular composition obtained directly from an amino acid fermentation broth or its treated solution by concentration, drying and granulation. As disclosed in e.g. French Patent Application Publication No. 2,217,347, Japanese Patent Laid-Open Nos. Sho 56-35962 (35962/1981) and Hei 5-192089 (192089/1993), dry composition containing amino acid for use as feed additive may be easily and cheaply obtained.
Although the above two processes are intended to prepare amino acid feed additive as solid material, they have a common problem as stated below. That is, although the compounding ratio of the amino acid feed additive to the mixing feed components must be set so as to become the amino acid content required depending on the age of animal to be fed, as a rule it is as very low as about 0.1 to 0.3% by weight. In addition, because the grain size distribution varies it is difficult to obtain a mixed feed having homogeneous quality by mechanical mixing procedure.
Also, for the feed industry handling an enormous amount of powdered and granular raw materials, an improvement in the powder characteristics of the powdered and granular raw materials has been required. For example, powdered CGM and CGF have characteristics that they have low bulk density and poor flowability and are apt to fly, and accordingly they have been required to improve their particle property from standpoint of view of transport cost and handling property.